Coffee manufacturers have advanced many processes aimed at upgrading the flavor quality of relatively poor quality green coffee beans over the years. One such process is taught by Ponzoni et al. in U.S. Pat. No. 3,767,418. Ponzoni et al. teach a method wherein green coffee is moisturized with water at a weight ratio of 0.25 to 1.5 green coffee to water. The moisturized green coffee is then steam-treated in an enclosed pressure vessel at a pressure of about 50 to 140 psig for from 1 to 10 minutes. The coffee so treated, after roasting, was found to be superior to a non-treated control. According to the Ponzoni et al. teaching, "below a steam pressure of about 50 p.s.i., the upgrading effect of treatment is insufficient to produce the desired characteristics in the final roasted and brewed coffee beverage" and "[a] steam pressure of 90 p.s.i. for treating the wetted green coffee has been found most desirable and a preferred operating range is from 70-110 psi steam pressure."
Another prior art process is described in U.S. Pat. No. 2,278,473 to Musher which teaches treatment of green or roasted coffee beans at a moisture level below about 20 to 25% by weight.
U.S. Pat. No. 4,540,591 to Dar et al. teaches a method for treating Robusta coffee beans wherein the beans are steam treated at a pressure of 7 to 10 atmospheres in a pressure vessel for 10 to 15 minutes with a continuous vent, discharged and then roasted. U.S. Pat. No. 3,991,223 to Baron et al. teaches a method for modifying the flavor and aroma of a steamed coffee aroma.
It is an object of the present invention to identify an efficient method for upgrading the quality of poor quality beans.
It is a further object to upgrade the quality of poor quality beans with a minimal level of energy consumption.
These and other objects of the invention will become apparent as the invention is described in detail below.